include/linux/rmap.h

   1 #ifndef _LINUX_RMAP_H
   2 #define _LINUX_RMAP_H
   3 /*
   4  * Declarations for Reverse Mapping functions in mm/rmap.c
   5  */
   6
   7 #include <linux/list.h>
   8 #include <linux/slab.h>
   9 #include <linux/mm.h>
  10 #include <linux/spinlock.h>
  11
  12 /*
  13  * The anon_vma heads a list of private "related" vmas, to scan if
  14  * an anonymous page pointing to this anon_vma needs to be unmapped:
  15  * the vmas on the list will be related by forking, or by splitting.
  16  *
  17  * Since vmas come and go as they are split and merged (particularly
  18  * in mprotect), the mapping field of an anonymous page cannot point
  19  * directly to a vma: instead it points to an anon_vma, on whose list
  20  * the related vmas can be easily linked or unlinked.
  21  *
  22  * After unlinking the last vma on the list, we must garbage collect
  23  * the anon_vma object itself: we're guaranteed no page can be
  24  * pointing to this anon_vma once its vma list is empty.
  25  */
  26 struct anon_vma {
  27         spinlock_t lock;        /* Serialize access to vma list */
  28         struct list_head head;  /* List of private "related" vmas */
  29 };
  30
  31 #ifdef CONFIG_MMU
  32
  33 extern struct kmem_cache *anon_vma_cachep;
  34
  35 static inline struct anon_vma *anon_vma_alloc(void)
  36 {
  37         return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
  38 }
  39
  40 static inline void anon_vma_free(struct anon_vma *anon_vma)
  41 {
  42         kmem_cache_free(anon_vma_cachep, anon_vma);
  43 }
  44
  45 static inline void anon_vma_lock(struct vm_area_struct *vma)
  46 {
  47         struct anon_vma *anon_vma = vma->anon_vma;
  48         if (anon_vma)
  49                 spin_lock(&anon_vma->lock);
  50 }
  51
  52 static inline void anon_vma_unlock(struct vm_area_struct *vma)
  53 {
  54         struct anon_vma *anon_vma = vma->anon_vma;
  55         if (anon_vma)
  56                 spin_unlock(&anon_vma->lock);
  57 }
  58
  59 /*
  60  * anon_vma helper functions.
  61  */
  62 void anon_vma_init(void);       /* create anon_vma_cachep */
  63 int  anon_vma_prepare(struct vm_area_struct *);
  64 void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  65 void anon_vma_unlink(struct vm_area_struct *);
  66 void anon_vma_link(struct vm_area_struct *);
  67 void __anon_vma_link(struct vm_area_struct *);
  68
  69 /*
  70  * rmap interfaces called when adding or removing pte of page
  71  */
  72 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  73 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  74 void page_add_file_rmap(struct page *);
  75 void page_remove_rmap(struct page *);
  76
  77 /**
  78  * page_dup_rmap - duplicate pte mapping to a page
  79  * @page:       the page to add the mapping to
  80  *
  81  * For copy_page_range only: minimal extract from page_add_rmap,
  82  * avoiding unnecessary tests (already checked) so it's quicker.
  83  */
  84 static inline void page_dup_rmap(struct page *page)
  85 {
  86         atomic_inc(&page->_mapcount);
  87 }
  88
  89 /*
  90  * Called from mm/vmscan.c to handle paging out
  91  */
  92 int page_referenced(struct page *, int is_locked);
  93 int try_to_unmap(struct page *, int ignore_refs);
  94
  95 /*
  96  * Called from mm/filemap_xip.c to unmap empty zero page
  97  */
  98 pte_t *page_check_address(struct page *, struct mm_struct *,
  99                                 unsigned long, spinlock_t **);
 100
 101 /*
 102  * Used by swapoff to help locate where page is expected in vma.
 103  */
 104 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 105
 106 /*
 107  * Cleans the PTEs of shared mappings.
 108  * (and since clean PTEs should also be readonly, write protects them too)
 109  *
 110  * returns the number of cleaned PTEs.
 111  */
 112 int page_mkclean(struct page *);
 113
 114 #else   /* !CONFIG_MMU */
 115
 116 #define anon_vma_init()         do {} while (0)
 117 #define anon_vma_prepare(vma)   (0)
 118 #define anon_vma_link(vma)      do {} while (0)
 119
 120 #define page_referenced(page,l) TestClearPageReferenced(page)
 121 #define try_to_unmap(page, refs) SWAP_FAIL
 122
 123 static inline int page_mkclean(struct page *page)
 124 {
 125         return 0;
 126 }
 127
 128
 129 #endif  /* CONFIG_MMU */
 130
 131 /*
 132  * Return values of try_to_unmap
 133  */
 134 #define SWAP_SUCCESS    0
 135 #define SWAP_AGAIN      1
 136 #define SWAP_FAIL       2
 137
 138 #endif  /* _LINUX_RMAP_H */